Knee ankylosis can vary in severity but to have functional range, patients need to be able to bend their knee more than 90 degrees. Knee ankylosis can have many underlying causes but eventually results in the contracture of the quadriceps muscle. Therefore, to be able regain range of motion, the quadriceps muscle needs to be released from its origin at the top of the femur. The Judet Quadricepsplasty technique involves releasing the knee and quadricep muscles in order to improve range of motion and function. This release is usually preformed from the knee, up the leg, along the entire femur on the anterior side all the way up to the hip joint.